Two wrenching scenes in Philip Roth's Letting Go

Examples of great, difficult, scenes in Philip Roth's writing, from 4th section, Three Women, in his first novel, "Letting Go" - the section begins with Gabe and Martha, now living together along with her two young children, preparing for a diner party (we gradually learn that guests will be Libby and Paul Herz, Gabe's main antagonists and counterpoints in this long novel) - and Gabe and Martha squabble painfully, relentlessly, mostly about $, but it's obvious that it's not about $ it's about power and the difficulty of two adults building some kind of relationship and commitment - she obviously wants G to marry her, though does she really love him or does she just want to be married, to have someone to help her with her kids, her life? - he's obviously not ready and not ready for her - as his eyes, and mind, keep wandering onto others, imagining what life would be like with them, etc. - the dinner party is a horror, they all say terrible things to one another, it's almost Albee-esque. Second wrenching scene, as this section continues, and we are now in the mind of Libby Herz, aware of her weaknesses and frailties, her hypochondria, her inability to do anything with her life, and we see through her eyes the terrible poverty in which she and Paul live - a few years earlier it would have been and was genteel grad-school poverty, la bue, as in nostalgia for, but now Paul is a prof at U Chicago, they should be more prosperous, comfortable, but their lives are terrible, he is trying to write a novel, he obviously never will, he obviously will not keep this fill-in job, they are destined for trouble - and then she gets a visit from the guy from an adoption agency and the visit is a horror, she is obviously disturbed and unfit and she knows this - she is ruining everything. Where can this lead but down?